1. Field of the Invention
The present invention relates to magnetic memory and, more specifically, to addressing architecture for perpendicular giant magnetoresistance memory.
2. Description of the Related Art
Constructing random access memory for computers from magnetic elements has the advantages of very high reliability, non-volatility in the event of power loss and infinite lifetime under use. It has been previously shown that magnetic information storage elements can be fabricated by exploiting giant magnetoresistance (GMR) multilayer materials in which the current is propagated perpendicular to the planes of the layers (CPP). See, e.g., U.S. Pat. No. 5,477,482 to Prinz, the entire contents of which are incorporated herein by reference. These elements can be formed into a series-resistance line as shown in FIG. 1. These lines are most easily fabricated by multiple depositions and lithographic patterning on an appropriate substrate.
Although the series-resistance line construction (sense lines) is useful for sensing the resistance of the memory storage elements (Bits), it lacks the means to address an individual Bit without some additional circuitry. Previously suggested approaches use additional electrically conducting elements located in the near-vicinity of each Bit to generate localized magnetic fields to alter the magnetic state of the nearest Bit without altering any other Bits. See, e.g., U.S. Pat. No. 6,391,483 to Zhu et al., the entire contents of which are incorporated herein by reference. These approaches are very demanding in their fabrication tolerances and are inefficient in their use of the expended electrical power to effect the magnetic state of the Bit.